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Title: Experimental investigation of the bubble motion and its ascension in a quiescent viscous liquid
Journal: Experimental Thermal and Fluid Science
Author: 1. Mohammad Reza Oshaghi, Mona Shahsavari, Hossein Afshin, Bahar Firoozabadi
Year: 2019
Address: 1. School of Mechanical Engineering, Sharif University of Technology, Tehran, 11155-9567,Iran.
Abstract: In the present research, the rising behavior of air bubble in a viscous liquid is investigated experimentally. Aqueous solutions of glycerol and CMC were used as the Newtonian and shear-thinning non-Newtonian viscous liquids, respectively. The bubble is formed via injection of air by a syringe pump and rises in the quiescent viscous liquid. The process was captured using a high-speed camera (1000 fps) and was post processed to obtain the bubble characteristics such as the center of mass and aspect ratio. The experimental results were verified using the existing literatures and the non-dimensional numbers were reduced to two (Velocity number and Flow number) by lumping the parameters. In addition, an empirical correlation was presented for the Velocity number at the moment of detachment based on the Flow number. In our experiments, three regimes were observed during the bubble rise after its detachment. In regime 1, the bubble shape oscillates between disk and hemisphere. In regime 2, the bubble gradually deforms into an ellipsoidal shape and in regime 3, the bubble shape remains nearly unchanged. Furthermore, the results indicated that the velocity behavior is influenced by the shape of the bubble: in regime 1, the velocity fluctuates. In regime 2, the velocity decreases temporarily and then increases toward the terminal velocity and finally in regime 3, the velocity increases or decreases monotonically toward the terminal velocity. Also, a criterion was found for the Velocity number in order to simultaneously predict the regime of bubble rise in a viscous liquid for Newtonian and non-Newtonian fluids.
Keywords: Bubble Rising, Bubble shape, Viscous liquid, Velocity number, Shear-thinning fluid
Application: Fluid Mechanics
Product Model 1: Syringe Pump
Product Model 2:
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